Hand tools with helical drive mechanisms are widely employed for driving tool bits such as screwdriver blades, drill bits, sockets and the like. The user is able to apply axial force on the tool handle which produces rotation of the drive shank or spindle as it moves upwardly into a bore in the handle against the biasing action of a spring therewithin. To effect the rotational movement of the shank in response to the axial pressure, it has been customary to employ a tubular element which has a helical groove formed along a bore therewithin and a helical thread on the drive shank or spindle.
Generally, the assembly for such tools has included an elongated tubular member designed to fit within a bore in the handle and having the helical groove portion at its outer end, most usually in a separate element assembled therewithin. The compression spring is disposed within the tubular element and a spring guide member is also usually provided therewithin. In assembling the tool, the tubular element, spring member and helical nut member are assembled together with the drive shank. This entire subassembly is then inserted into the bore of the handle.
It is an object of the present invention to provide a hand tool with a helical drive which uses a minimum of parts and which may be readily assembled.
It is also an object to provide such a hand tool which may be fabricated relatively economically and which is durable in operation.
Another object is to provide a method for rapidly assembling hand tools with helical drives from a minimum of parts.